It has long been recognized that heavy metals are a very serious environmental pollutant since they are poisonous to many forms of life including man and are frequently introduced to natural waters, including streams, ponds, lakes and the oceans. This is very serious, not only due to the direct contamination of such waters with consequent detrimental or even lethal effect on the life of aquatic organisims which enter into the food chain, but due to the fact that heavy metals tend to build up in such organisims with resulting increased concentration over a period of time. Indeed, the heavy metal concentrations in many types of fish and other sea food has reached a level in some localities such that it is not recommended that these foods by eaten by man. This problem is itself aggravated by the tendency of the heavy metals to build up in concentration in any organism which ingests them, including man. Therefore, human health may be and indeed has been seriously adversely affected not only by drinking water containing heavy metals but by ingesting fish or sea food from such waters or even eating animal or vegetable food raised using such waters.
This problem has become so serious that the U.S. Environmental Protection Agency (EPA) has established very stringent standards for heavy metals in industrial or other waste waters which are discharged to the environment. In particular, EPA regulations have recently been promulgated for regulating the amount of heavy metals discharged by the electroplating industry into waters subject to processing by Publicly Owned Treatment Works (POTW) for subsequent drinking purposes. Similar EPA regulations are expected to be promulgated for as many as 20 other categories of industry.
While a great deal of technology exists concerning the removal of heavy metals from wastewater or other aqueous solutions, the new EPA regulations for the electroplating industry and further regulations to be expected in the future clearly require improved technology to meet the stringent standards for direct discharge of heavy metals into receiving streams or the indirect discharge into the POTW referred to above.